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|
/*
* Dropbear SSH
*
* Copyright (c) 2002-2004 Matt Johnston
* All rights reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE. */
/* Handle the multiplexed channels, such as sessions, x11, agent connections */
#include "includes.h"
#include "session.h"
#include "packet.h"
#include "ssh.h"
#include "buffer.h"
#include "circbuffer.h"
#include "dbutil.h"
#include "channel.h"
#include "ssh.h"
#include "listener.h"
static void send_msg_channel_open_failure(unsigned int remotechan, int reason,
const unsigned char *text, const unsigned char *lang);
static void send_msg_channel_open_confirmation(struct Channel* channel,
unsigned int recvwindow,
unsigned int recvmaxpacket);
static void writechannel(struct Channel* channel, int fd, circbuffer *cbuf);
static void send_msg_channel_window_adjust(struct Channel *channel,
unsigned int incr);
static void send_msg_channel_data(struct Channel *channel, int isextended,
unsigned int exttype);
static void send_msg_channel_eof(struct Channel *channel);
static void send_msg_channel_close(struct Channel *channel);
static void removechannel(struct Channel *channel);
static void deletechannel(struct Channel *channel);
static void checkinitdone(struct Channel *channel);
static void checkclose(struct Channel *channel);
static void closeinfd(struct Channel * channel);
static void closeoutfd(struct Channel * channel, int fd);
static void closechanfd(struct Channel *channel, int fd, int how);
#define FD_UNINIT (-2)
#define FD_CLOSED (-1)
/* Initialise all the channels */
void chaninitialise(const struct ChanType *chantypes[]) {
/* may as well create space for a single channel */
ses.channels = (struct Channel**)m_malloc(sizeof(struct Channel*));
ses.chansize = 1;
ses.channels[0] = NULL;
ses.chancount = 0;
ses.chantypes = chantypes;
#ifdef USING_LISTENERS
listeners_initialise();
#endif
}
/* Clean up channels, freeing allocated memory */
void chancleanup() {
unsigned int i;
TRACE(("enter chancleanup"));
for (i = 0; i < ses.chansize; i++) {
if (ses.channels[i] != NULL) {
TRACE(("channel %d closing", i));
removechannel(ses.channels[i]);
}
}
m_free(ses.channels);
TRACE(("leave chancleanup"));
}
/* Create a new channel entry, send a reply confirm or failure */
/* If remotechan, transwindow and transmaxpacket are not know (for a new
* outgoing connection, with them to be filled on confirmation), they should
* all be set to 0 */
struct Channel* newchannel(unsigned int remotechan,
const struct ChanType *type,
unsigned int transwindow, unsigned int transmaxpacket) {
struct Channel * newchan;
unsigned int i, j;
TRACE(("enter newchannel"));
/* first see if we can use existing channels */
for (i = 0; i < ses.chansize; i++) {
if (ses.channels[i] == NULL) {
break;
}
}
/* otherwise extend the list */
if (i == ses.chansize) {
if (ses.chansize >= MAX_CHANNELS) {
TRACE(("leave newchannel: max chans reached"));
return NULL;
}
/* extend the channels */
ses.channels = (struct Channel**)m_realloc(ses.channels,
(ses.chansize+CHAN_EXTEND_SIZE)*sizeof(struct Channel*));
ses.chansize += CHAN_EXTEND_SIZE;
/* set the new channels to null */
for (j = i; j < ses.chansize; j++) {
ses.channels[j] = NULL;
}
}
newchan = (struct Channel*)m_malloc(sizeof(struct Channel));
newchan->type = type;
newchan->index = i;
newchan->sentclosed = newchan->recvclosed = 0;
newchan->senteof = newchan->recveof = 0;
newchan->remotechan = remotechan;
newchan->transwindow = transwindow;
newchan->transmaxpacket = transmaxpacket;
newchan->typedata = NULL;
newchan->infd = FD_UNINIT;
newchan->outfd = FD_UNINIT;
newchan->errfd = FD_CLOSED; /* this isn't always set to start with */
newchan->initconn = 0;
newchan->writebuf = cbuf_new(RECV_MAXWINDOW);
newchan->extrabuf = NULL; /* The user code can set it up */
newchan->recvwindow = RECV_MAXWINDOW;
newchan->recvdonelen = 0;
newchan->recvmaxpacket = RECV_MAXPACKET;
ses.channels[i] = newchan;
ses.chancount++;
TRACE(("leave newchannel"));
return newchan;
}
/* Get the channel structure corresponding to a channel number */
struct Channel* getchannel(unsigned int chan) {
if (chan >= ses.chansize || ses.channels[chan] == NULL) {
return NULL;
}
return ses.channels[chan];
}
/* Iterate through the channels, performing IO if available */
void channelio(fd_set *readfd, fd_set *writefd) {
struct Channel *channel;
unsigned int i;
int ret;
/* iterate through all the possible channels */
for (i = 0; i < ses.chansize; i++) {
channel = ses.channels[i];
if (channel == NULL) {
/* only process in-use channels */
continue;
}
/* read from program/pipe stdout */
if (channel->outfd >= 0 && FD_ISSET(channel->outfd, readfd)) {
send_msg_channel_data(channel, 0, 0);
}
/* read from program/pipe stderr */
if (channel->extrabuf == NULL &&
channel->errfd >= 0 && FD_ISSET(channel->errfd, readfd)) {
send_msg_channel_data(channel, 1, SSH_EXTENDED_DATA_STDERR);
}
/* if we can read from the infd, it might be closed, so we try to
* see if it has errors */
if (channel->infd >= 0 && channel->infd != channel->outfd
&& FD_ISSET(channel->infd, readfd)) {
if (channel->initconn) {
/* Handling for "in progress" connection - this is needed
* to avoid spinning 100% CPU when we connect to a server
* which doesn't send anything (tcpfwding) */
checkinitdone(channel);
continue; /* Important not to use the channel after
checkinitdone(), as it may be NULL */
}
ret = write(channel->infd, NULL, 0); /* Fake write */
if (ret < 0 && errno != EINTR && errno != EAGAIN) {
closeinfd(channel);
}
}
/* write to program/pipe stdin */
if (channel->infd >= 0 && FD_ISSET(channel->infd, writefd)) {
if (channel->initconn) {
checkinitdone(channel);
continue; /* Important not to use the channel after
checkinitdone(), as it may be NULL */
}
writechannel(channel, channel->infd, channel->writebuf);
}
/* stderr for client mode */
if (channel->extrabuf != NULL
&& channel->errfd >= 0 && FD_ISSET(channel->errfd, writefd)) {
writechannel(channel, channel->errfd, channel->extrabuf);
}
/* now handle any of the channel-closing type stuff */
checkclose(channel);
} /* foreach channel */
/* Listeners such as TCP, X11, agent-auth */
#ifdef USING_LISTENERS
handle_listeners(readfd);
#endif
}
/* do all the EOF/close type stuff checking for a channel */
static void checkclose(struct Channel *channel) {
TRACE(("checkclose: infd %d, outfd %d, errfd %d, sentclosed %d, recvclosed %d",
channel->infd, channel->outfd,
channel->errfd, channel->sentclosed, channel->recvclosed));
TRACE(("writebuf %d extrabuf %s extrabuf %d",
cbuf_getused(channel->writebuf),
channel->writebuf,
channel->writebuf ? 0 : cbuf_getused(channel->extrabuf)));
if (!channel->sentclosed) {
/* check for exited - currently only used for server sessions,
* if the shell has exited etc */
if (channel->type->checkclose) {
if (channel->type->checkclose(channel)) {
closeinfd(channel);
}
}
if (!channel->senteof
&& channel->outfd == FD_CLOSED
&& (channel->extrabuf != NULL || channel->errfd == FD_CLOSED)) {
send_msg_channel_eof(channel);
}
if (channel->infd == FD_CLOSED
&& channel->outfd == FD_CLOSED
&& (channel->extrabuf != NULL || channel->errfd == FD_CLOSED)) {
send_msg_channel_close(channel);
}
}
/* When either party wishes to terminate the channel, it sends
* SSH_MSG_CHANNEL_CLOSE. Upon receiving this message, a party MUST
* send back a SSH_MSG_CHANNEL_CLOSE unless it has already sent this
* message for the channel. The channel is considered closed for a
* party when it has both sent and received SSH_MSG_CHANNEL_CLOSE, and
* the party may then reuse the channel number. A party MAY send
* SSH_MSG_CHANNEL_CLOSE without having sent or received
* SSH_MSG_CHANNEL_EOF.
* (from draft-ietf-secsh-connect)
*/
if (channel->recvclosed) {
if (! channel->sentclosed) {
TRACE(("Sending MSG_CHANNEL_CLOSE in response to same."));
send_msg_channel_close(channel);
}
removechannel(channel);
}
}
/* Check whether a deferred (EINPROGRESS) connect() was successful, and
* if so, set up the channel properly. Otherwise, the channel is cleaned up, so
* it is important that the channel reference isn't used after a call to this
* function */
static void checkinitdone(struct Channel *channel) {
int val;
socklen_t vallen = sizeof(val);
TRACE(("enter checkinitdone"));
if (getsockopt(channel->infd, SOL_SOCKET, SO_ERROR, &val, &vallen)
|| val != 0) {
send_msg_channel_open_failure(channel->remotechan,
SSH_OPEN_CONNECT_FAILED, "", "");
close(channel->infd);
deletechannel(channel);
TRACE(("leave checkinitdone: fail"));
} else {
send_msg_channel_open_confirmation(channel, channel->recvwindow,
channel->recvmaxpacket);
channel->outfd = channel->infd;
channel->initconn = 0;
TRACE(("leave checkinitdone: success"));
}
}
/* Send the close message and set the channel as closed */
static void send_msg_channel_close(struct Channel *channel) {
TRACE(("enter send_msg_channel_close"));
/* XXX server */
if (channel->type->closehandler) {
channel->type->closehandler(channel);
}
CHECKCLEARTOWRITE();
buf_putbyte(ses.writepayload, SSH_MSG_CHANNEL_CLOSE);
buf_putint(ses.writepayload, channel->remotechan);
encrypt_packet();
channel->senteof = 1;
channel->sentclosed = 1;
TRACE(("leave send_msg_channel_close"));
}
/* call this when trans/eof channels are closed */
static void send_msg_channel_eof(struct Channel *channel) {
TRACE(("enter send_msg_channel_eof"));
CHECKCLEARTOWRITE();
buf_putbyte(ses.writepayload, SSH_MSG_CHANNEL_EOF);
buf_putint(ses.writepayload, channel->remotechan);
encrypt_packet();
channel->senteof = 1;
TRACE(("leave send_msg_channel_eof"));
}
/* Called to write data out to the local side of the channel.
* Only called when we know we can write to a channel, writes as much as
* possible */
static void writechannel(struct Channel* channel, int fd, circbuffer *cbuf) {
int len, maxlen;
TRACE(("enter writechannel"));
maxlen = cbuf_readlen(cbuf);
/* Write the data out */
len = write(fd, cbuf_readptr(cbuf, maxlen), maxlen);
if (len <= 0) {
if (len < 0 && errno != EINTR) {
/* no more to write - we close it even if the fd was stderr, since
* that's a nasty failure too */
closeinfd(channel);
}
TRACE(("leave writechannel: len <= 0"));
return;
}
cbuf_incrread(cbuf, len);
channel->recvdonelen += len;
if (fd == channel->infd && len == maxlen && channel->recveof) {
/* Check if we're closing up */
closeinfd(channel);
TRACE(("leave writechannel: recveof set"));
return;
}
/* Window adjust handling */
if (channel->recvdonelen >= RECV_WINDOWEXTEND) {
/* Set it back to max window */
send_msg_channel_window_adjust(channel, channel->recvdonelen);
channel->recvwindow += channel->recvdonelen;
channel->recvdonelen = 0;
}
assert(channel->recvwindow <= RECV_MAXWINDOW);
assert(channel->recvwindow <= cbuf_getavail(channel->writebuf));
assert(channel->extrabuf == NULL ||
channel->recvwindow <= cbuf_getavail(channel->extrabuf));
TRACE(("leave writechannel"));
}
/* Set the file descriptors for the main select in session.c
* This avoid channels which don't have any window available, are closed, etc*/
void setchannelfds(fd_set *readfd, fd_set *writefd) {
unsigned int i;
struct Channel * channel;
for (i = 0; i < ses.chansize; i++) {
channel = ses.channels[i];
if (channel == NULL) {
continue;
}
/* Stuff to put over the wire */
if (channel->transwindow > 0) {
if (channel->outfd >= 0) {
FD_SET(channel->outfd, readfd);
}
if (channel->extrabuf == NULL && channel->errfd >= 0) {
FD_SET(channel->errfd, readfd);
}
}
/* For checking FD status (ie closure etc) - we don't actually
* read data from infd */
TRACE(("infd = %d, outfd %d, errfd %d, bufused %d",
channel->infd, channel->outfd,
channel->errfd,
cbuf_getused(channel->writebuf) ));
if (channel->infd >= 0 && channel->infd != channel->outfd) {
FD_SET(channel->infd, readfd);
}
/* Stuff from the wire, to local program/shell/user etc */
if ((channel->infd >= 0 && cbuf_getused(channel->writebuf) > 0 )
|| channel->initconn) {
FD_SET(channel->infd, writefd);
}
if (channel->extrabuf != NULL && channel->errfd >= 0
&& cbuf_getused(channel->extrabuf) > 0 ) {
FD_SET(channel->errfd, writefd);
}
} /* foreach channel */
#ifdef USING_LISTENERS
set_listener_fds(readfd);
#endif
}
/* handle the channel EOF event, by closing the channel filedescriptor. The
* channel isn't closed yet, it is left until the incoming (from the program
* etc) FD is also EOF */
void recv_msg_channel_eof() {
unsigned int chan;
struct Channel * channel;
TRACE(("enter recv_msg_channel_eof"));
chan = buf_getint(ses.payload);
channel = getchannel(chan);
if (channel == NULL) {
dropbear_exit("EOF for unknown channel");
}
channel->recveof = 1;
if (cbuf_getused(channel->writebuf) == 0
&& (channel->extrabuf == NULL
|| cbuf_getused(channel->extrabuf) == 0)) {
closeinfd(channel);
}
TRACE(("leave recv_msg_channel_eof"));
}
/* Handle channel closure(), respond in kind and close the channels */
void recv_msg_channel_close() {
unsigned int chan;
struct Channel * channel;
TRACE(("enter recv_msg_channel_close"));
chan = buf_getint(ses.payload);
TRACE(("close channel = %d", chan));
channel = getchannel(chan);
if (channel == NULL) {
/* disconnect ? */
dropbear_exit("Close for unknown channel");
}
channel->recveof = 1;
channel->recvclosed = 1;
if (channel->sentclosed) {
removechannel(channel);
}
TRACE(("leave recv_msg_channel_close"));
}
/* Remove a channel entry, this is only executed after both sides have sent
* channel close */
static void removechannel(struct Channel * channel) {
TRACE(("enter removechannel"));
TRACE(("channel index is %d", channel->index));
cbuf_free(channel->writebuf);
channel->writebuf = NULL;
if (channel->extrabuf) {
cbuf_free(channel->extrabuf);
channel->extrabuf = NULL;
}
/* close the FDs in case they haven't been done
* yet (ie they were shutdown etc */
close(channel->infd);
close(channel->outfd);
close(channel->errfd);
channel->typedata = NULL;
deletechannel(channel);
TRACE(("leave removechannel"));
}
/* Remove a channel entry */
static void deletechannel(struct Channel *channel) {
ses.channels[channel->index] = NULL;
m_free(channel);
ses.chancount--;
}
/* Handle channel specific requests, passing off to corresponding handlers
* such as chansession or x11fwd */
void recv_msg_channel_request() {
unsigned int chan;
struct Channel *channel;
TRACE(("enter recv_msg_channel_request"));
chan = buf_getint(ses.payload);
channel = getchannel(chan);
if (channel == NULL) {
/* disconnect ? */
dropbear_exit("Unknown channel");
}
if (channel->type->reqhandler) {
channel->type->reqhandler(channel);
} else {
send_msg_channel_failure(channel);
}
TRACE(("leave recv_msg_channel_request"));
}
/* Reads data from the server's program/shell/etc, and puts it in a
* channel_data packet to send.
* chan is the remote channel, isextended is 0 if it is normal data, 1
* if it is extended data. if it is extended, then the type is in
* exttype */
static void send_msg_channel_data(struct Channel *channel, int isextended,
unsigned int exttype) {
buffer *buf;
int len;
unsigned int maxlen;
int fd;
/* TRACE(("enter send_msg_channel_data"));
TRACE(("extended = %d type = %d", isextended, exttype));*/
CHECKCLEARTOWRITE();
assert(!channel->sentclosed);
if (isextended) {
fd = channel->errfd;
} else {
fd = channel->outfd;
}
assert(fd >= 0);
maxlen = MIN(channel->transwindow, channel->transmaxpacket);
/* -(1+4+4) is SSH_MSG_CHANNEL_DATA, channel number, string length, and
* exttype if is extended */
maxlen = MIN(maxlen,
ses.writepayload->size - 1 - 4 - 4 - (isextended ? 4 : 0));
if (maxlen == 0) {
TRACE(("leave send_msg_channel_data: no window"));
return; /* the data will get written later */
}
/* read the data */
TRACE(("maxlen %d", maxlen));
buf = buf_new(maxlen);
TRACE(("buf pos %d data %x", buf->pos, buf->data));
len = read(fd, buf_getwriteptr(buf, maxlen), maxlen);
if (len <= 0) {
/* on error/eof, send eof */
if (len == 0 || errno != EINTR) {
closeoutfd(channel, fd);
}
buf_free(buf);
buf = NULL;
TRACE(("leave send_msg_channel_data: read err or EOF for fd %d",
channel->index));
return;
}
buf_incrlen(buf, len);
buf_putbyte(ses.writepayload,
isextended ? SSH_MSG_CHANNEL_EXTENDED_DATA : SSH_MSG_CHANNEL_DATA);
buf_putint(ses.writepayload, channel->remotechan);
if (isextended) {
buf_putint(ses.writepayload, exttype);
}
buf_putstring(ses.writepayload, buf_getptr(buf, len), len);
buf_free(buf);
buf = NULL;
channel->transwindow -= len;
encrypt_packet();
TRACE(("leave send_msg_channel_data"));
}
/* We receive channel data */
void recv_msg_channel_data() {
unsigned int chan;
struct Channel *channel;
chan = buf_getint(ses.payload);
channel = getchannel(chan);
if (channel == NULL) {
dropbear_exit("Unknown channel");
}
common_recv_msg_channel_data(channel, channel->infd, channel->writebuf);
}
/* Shared for data and stderr data - when we receive data, put it in a buffer
* for writing to the local file descriptor */
void common_recv_msg_channel_data(struct Channel *channel, int fd,
circbuffer * cbuf) {
unsigned int datalen;
unsigned int maxdata;
unsigned int buflen;
unsigned int len;
TRACE(("enter recv_msg_channel_data"));
if (channel->recveof) {
dropbear_exit("received data after eof");
}
if (fd < 0) {
dropbear_exit("received data with bad infd");
}
datalen = buf_getint(ses.payload);
maxdata = cbuf_getavail(cbuf);
/* Whilst the spec says we "MAY ignore data past the end" this could
* lead to corrupted file transfers etc (chunks missed etc). It's better to
* just die horribly */
if (datalen > maxdata) {
dropbear_exit("Oversized packet");
}
/* We may have to run throught twice, if the buffer wraps around. Can't
* just "leave it for next time" like with writechannel, since this
* is payload data */
len = datalen;
while (len > 0) {
buflen = cbuf_writelen(cbuf);
buflen = MIN(buflen, len);
memcpy(cbuf_writeptr(cbuf, buflen),
buf_getptr(ses.payload, buflen), buflen);
cbuf_incrwrite(cbuf, buflen);
buf_incrpos(ses.payload, buflen);
len -= buflen;
}
assert(channel->recvwindow >= datalen);
channel->recvwindow -= datalen;
assert(channel->recvwindow <= RECV_MAXWINDOW);
TRACE(("leave recv_msg_channel_data"));
}
/* Increment the outgoing data window for a channel - the remote end limits
* the amount of data which may be transmitted, this window is decremented
* as data is sent, and incremented upon receiving window-adjust messages */
void recv_msg_channel_window_adjust() {
unsigned int chan;
struct Channel * channel;
unsigned int incr;
chan = buf_getint(ses.payload);
channel = getchannel(chan);
if (channel == NULL) {
dropbear_exit("Unknown channel");
}
incr = buf_getint(ses.payload);
TRACE(("received window increment %d", incr));
incr = MIN(incr, MAX_TRANS_WIN_INCR);
channel->transwindow += incr;
channel->transwindow = MIN(channel->transwindow, MAX_TRANS_WINDOW);
}
/* Increment the incoming data window for a channel, and let the remote
* end know */
static void send_msg_channel_window_adjust(struct Channel* channel,
unsigned int incr) {
TRACE(("sending window adjust %d", incr));
CHECKCLEARTOWRITE();
buf_putbyte(ses.writepayload, SSH_MSG_CHANNEL_WINDOW_ADJUST);
buf_putint(ses.writepayload, channel->remotechan);
buf_putint(ses.writepayload, incr);
encrypt_packet();
}
/* Handle a new channel request, performing any channel-type-specific setup */
/* XXX server */
void recv_msg_channel_open() {
unsigned char *type;
unsigned int typelen;
unsigned int remotechan, transwindow, transmaxpacket;
struct Channel *channel;
const struct ChanType **cp;
const struct ChanType *chantype;
unsigned int errtype = SSH_OPEN_UNKNOWN_CHANNEL_TYPE;
int ret;
TRACE(("enter recv_msg_channel_open"));
/* get the packet contents */
type = buf_getstring(ses.payload, &typelen);
remotechan = buf_getint(ses.payload);
transwindow = buf_getint(ses.payload);
transwindow = MIN(transwindow, MAX_TRANS_WINDOW);
transmaxpacket = buf_getint(ses.payload);
transmaxpacket = MIN(transmaxpacket, MAX_TRANS_PAYLOAD_LEN);
/* figure what type of packet it is */
if (typelen > MAX_NAME_LEN) {
goto failure;
}
/* Get the channel type. Client and server style invokation will set up a
* different list for ses.chantypes at startup. We just iterate through
* this list and find the matching name */
for (cp = &ses.chantypes[0], chantype = (*cp);
chantype != NULL;
cp++, chantype = (*cp)) {
if (strcmp(type, chantype->name) == 0) {
break;
}
}
if (chantype == NULL) {
TRACE(("No matching type for '%s'", type));
goto failure;
}
TRACE(("matched type '%s'", type));
/* create the channel */
channel = newchannel(remotechan, chantype, transwindow, transmaxpacket);
if (channel == NULL) {
TRACE(("newchannel returned NULL"));
goto failure;
}
if (channel->type->inithandler) {
ret = channel->type->inithandler(channel);
if (ret > 0) {
if (ret == SSH_OPEN_IN_PROGRESS) {
/* We'll send the confirmation later */
goto cleanup;
}
errtype = ret;
deletechannel(channel);
TRACE(("inithandler returned failure %d", ret));
goto failure;
}
}
/* success */
send_msg_channel_open_confirmation(channel, channel->recvwindow,
channel->recvmaxpacket);
goto cleanup;
failure:
TRACE(("recv_msg_channel_open failure"));
send_msg_channel_open_failure(remotechan, errtype, "", "");
cleanup:
m_free(type);
TRACE(("leave recv_msg_channel_open"));
}
/* Send a failure message */
void send_msg_channel_failure(struct Channel *channel) {
TRACE(("enter send_msg_channel_failure"));
CHECKCLEARTOWRITE();
buf_putbyte(ses.writepayload, SSH_MSG_CHANNEL_FAILURE);
buf_putint(ses.writepayload, channel->remotechan);
encrypt_packet();
TRACE(("leave send_msg_channel_failure"));
}
/* Send a success message */
void send_msg_channel_success(struct Channel *channel) {
TRACE(("enter send_msg_channel_success"));
CHECKCLEARTOWRITE();
buf_putbyte(ses.writepayload, SSH_MSG_CHANNEL_SUCCESS);
buf_putint(ses.writepayload, channel->remotechan);
encrypt_packet();
TRACE(("leave send_msg_channel_success"));
}
/* Send a channel open failure message, with a corresponding reason
* code (usually resource shortage or unknown chan type) */
static void send_msg_channel_open_failure(unsigned int remotechan,
int reason, const unsigned char *text, const unsigned char *lang) {
TRACE(("enter send_msg_channel_open_failure"));
CHECKCLEARTOWRITE();
buf_putbyte(ses.writepayload, SSH_MSG_CHANNEL_OPEN_FAILURE);
buf_putint(ses.writepayload, remotechan);
buf_putint(ses.writepayload, reason);
buf_putstring(ses.writepayload, text, strlen((char*)text));
buf_putstring(ses.writepayload, lang, strlen((char*)lang));
encrypt_packet();
TRACE(("leave send_msg_channel_open_failure"));
}
/* Confirm a channel open, and let the remote end know what number we've
* allocated and the receive parameters */
static void send_msg_channel_open_confirmation(struct Channel* channel,
unsigned int recvwindow,
unsigned int recvmaxpacket) {
TRACE(("enter send_msg_channel_open_confirmation"));
CHECKCLEARTOWRITE();
buf_putbyte(ses.writepayload, SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
buf_putint(ses.writepayload, channel->remotechan);
buf_putint(ses.writepayload, channel->index);
buf_putint(ses.writepayload, recvwindow);
buf_putint(ses.writepayload, recvmaxpacket);
encrypt_packet();
TRACE(("leave send_msg_channel_open_confirmation"));
}
#ifdef USING_LISTENERS
/* Create a new channel, and start the open request. This is intended
* for X11, agent, tcp forwarding, and should be filled with channel-specific
* options, with the calling function calling encrypt_packet() after
* completion. It is mandatory for the caller to encrypt_packet() if
* DROPBEAR_SUCCESS is returned */
int send_msg_channel_open_init(int fd, const struct ChanType *type) {
struct Channel* chan;
TRACE(("enter send_msg_channel_open_init()"));
chan = newchannel(0, type, 0, 0);
if (!chan) {
TRACE(("leave send_msg_channel_open_init() - FAILED in newchannel()"));
return DROPBEAR_FAILURE;
}
/* set fd non-blocking */
setnonblocking(fd);
chan->infd = chan->outfd = fd;
ses.maxfd = MAX(ses.maxfd, fd);
/* now open the channel connection */
CHECKCLEARTOWRITE();
buf_putbyte(ses.writepayload, SSH_MSG_CHANNEL_OPEN);
buf_putstring(ses.writepayload, type->name, strlen(type->name));
buf_putint(ses.writepayload, chan->index);
buf_putint(ses.writepayload, RECV_MAXWINDOW);
buf_putint(ses.writepayload, RECV_MAXPACKET);
TRACE(("leave send_msg_channel_open_init()"));
return DROPBEAR_SUCCESS;
}
/* Confirmation that our channel open request (for forwardings) was
* successful*/
void recv_msg_channel_open_confirmation() {
unsigned int chan;
struct Channel * channel;
int ret;
TRACE(("enter recv_msg_channel_open_confirmation"));
chan = buf_getint(ses.payload);
channel = getchannel(chan);
if (channel == NULL) {
dropbear_exit("Unknown channel");
}
channel->remotechan = buf_getint(ses.payload);
channel->transwindow = buf_getint(ses.payload);
channel->transmaxpacket = buf_getint(ses.payload);
TRACE(("new chan remote %d localho %d", channel->remotechan, chan));
/* Run the inithandler callback */
if (channel->type->inithandler) {
ret = channel->type->inithandler(channel);
if (ret > 0) {
removechannel(channel);
TRACE(("inithandler returned failure %d", ret));
}
}
TRACE(("leave recv_msg_channel_open_confirmation"));
}
/* Notification that our channel open request failed */
void recv_msg_channel_open_failure() {
unsigned int chan;
struct Channel * channel;
chan = buf_getbyte(ses.payload);
channel = getchannel(chan);
if (channel == NULL) {
dropbear_exit("Unknown channel");
}
removechannel(channel);
}
/* close a stdout/stderr fd */
static void closeoutfd(struct Channel * channel, int fd) {
/* don't close it if it is the same as infd,
* unless infd is already set -1 */
TRACE(("enter closeoutfd"));
closechanfd(channel, fd, 0);
TRACE(("leave closeoutfd"));
}
/* close a stdin fd */
static void closeinfd(struct Channel * channel) {
TRACE(("enter closeinfd"));
closechanfd(channel, channel->infd, 1);
TRACE(("leave closeinfd"));
}
/* close a fd, how is 0 for stdout/stderr, 1 for stdin */
static void closechanfd(struct Channel *channel, int fd, int how) {
int closein = 0, closeout = 0;
/* XXX server */
if (channel->type->sepfds) {
shutdown(fd, how);
if (how == 0) {
closeout = 1;
} else {
closein = 1;
}
} else {
close(fd);
closein = closeout = 1;
}
if (closeout && fd == channel->outfd) {
channel->outfd = FD_CLOSED;
}
if (closeout && (channel->extrabuf == NULL) && (fd == channel->errfd)) {
channel->errfd = FD_CLOSED;
}
if (closein && fd == channel->infd) {
channel->infd = FD_CLOSED;
}
if (closein && (channel->extrabuf != NULL) && (fd == channel->errfd)) {
channel->errfd = FD_CLOSED;
}
}
#endif /* USING_LISTENERS */
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